JP2008543710A - Method for producing a solid mixture containing nanoparticulate lanthanoid / boron-compound or nanoparticulate lanthanoid / boron-compound - Google Patents

Abstract

  The present invention relates to a process for the production of an essentially isometric nanoparticulate lanthanoid / boron-compound, or a solid mixture containing essentially isometric nanoparticulate lanthanoid / boron-compound, said process comprising: A) i) one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid hydrides, lanthanoid chalcogenides, lanthanoid halides, lanthanoid borates and mixed compounds of said lanthanoid compounds, ii ) One or more compounds selected from the group consisting of crystalline boron, amorphous boron, boron carbides, borohydrides and boron halides and iii) hydrogen, carbon, organic compounds, alkaline earth metals And optionally one or more selected from the group consisting of alkaline earth metal hydrides The above reducing agent is dispersed in an inert carrier gas and mixed with each other; b) the mixture of components i), ii) and optionally iii) in the inert carrier gas is reacted with each other by heat treatment in the reaction zone. C) subjecting the reaction product obtained by heat treatment in step b) to rapid cooling and d) subsequently causing separation of the cooled reaction product in step c), in which case in step c) The cooling conditions are selected such that the reaction product consists essentially of isometric nanoparticulate lanthanoid / boron-compound or contains essentially isometric nanoparticulate lanthanoid / boron-compound. Is characterized by

Description

The present invention relates to a process for the production of an essentially isometrischen nanoparticulate lanthanoid / boron-compound, or a solid mixture containing essentially isometric nanoparticulate lanthanoid / boron-compound, The method
a) i) one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid hydrides, lanthanoid chalcogenides, lanthanoid halides, lanthanoid borates and mixtures of the above lanthanoid compounds,
b) ii) one or more compounds selected from the group consisting of crystalline boron, amorphous boron, boron carbides, borohydrides and boron halides and iii) hydrogen, carbon, organic compounds, alkalis Optionally selected from the group consisting of earth metals and alkaline earth metal hydrides, one or more reducing agents dispersed in an inert carrier gas and mixed together;
c) reacting a mixture of components i), ii) and optionally iii) in an inert carrier gas with each other by heat treatment in the reaction zone;
d) subjecting the reaction product obtained by the heat treatment in step b) to rapid cooling, and e) subsequently causing separation of the cooled reaction product in step c),
In so doing, the cooling conditions in step c) are such that the reaction product consists essentially of an isometric nanoparticulate lanthanoid / boron compound, or an essentially isometric nanoparticulate lanthanoid / boron compound. Characterized by being selected to contain.

  Nanoparticulate lanthanoid / boron-compounds, in particular lanthanum hexaboride-nanoparticles, are superior in that they absorb predominantly near-infrared and far-infrared radiation. Accordingly, there is no lack of a wide variety of methods for producing such compounds, particularly lanthanum hexaboride, which is by far the most commonly used lanthanoid / boron-compound.

  Most manufacturing methods are based on conventional high temperature reactions of suitable lanthanoid precursor compounds and boron precursor compounds and grinding of the resulting coarse granular primary product, whereas nanoparticulate lanthanoid / boron compounds are directly applied. Methods of providing are also known.

  For example, nanoparticulate metal borides according to JP-B 06-039326 may be obtained by evaporation of borides of metals from groups Ia, IIa, IIIa, IVa, Va or VIa of the periodic table, or hydrogen. Plasma or hydrogen / inert gas-obtained by evaporation and subsequent condensation of the corresponding metal and boron mixture in plasma.

  The production of nanoparticulate metal borides by reaction of metal powder and / or metal boride powder and boron powder in an inert gas plasma is described in JP-A-2003-261323. Yes.

  Both of these plasma processes have in common to start with the corresponding metals or metal borides which are themselves usually expensive and thus usually obtainable only by energy-intensive and cost-intensive methods. Thus, for example, lanthanoid metals are usually produced from lanthanoid halides by molten salt electrolysis because the former exhibits a markedly base electrochemical behavior.

  The object of the present invention is therefore to provide a process for producing lanthanoid / boron compounds which makes it possible to start directly from an inexpensive lanthanoid compound.

  Accordingly, the method described at the beginning has been found.

As component i) of the process according to the invention one or more selected from the group consisting of lanthanoid hydroxides, lanthanoid hydrides, lanthanoid chalcogenides, lanthanoid halides, lanthanoid borates and mixtures of said lanthanoid compounds The lanthanoid compounds are worth considering. Suitable lanthanoid hydroxides, in particular trivalent lanthanoid hydroxides Ln (OH) ₃ (hereinafter lanthanoid elements or yttrium not otherwise specified are abbreviated as “Ln” according to common terminology), suitable lanthanoids As hydrides, compounds of LnH ₂ and LnH ₃ , as suitable lanthanoid chalcogenides, as compounds of LnS, LnSe and LnTe, in particular as compounds of Ln ₂ O ₃ and Ln ₂ S ₃ , as lanthanoid halides, in particular LnF ₃ , LnCl ₃ As LnBr ₃ and LnI ₃ and lanthanoid borates, mention may be made in particular of LnBO ₃ , Ln ₃ BO ₆ and Ln (BO ₂ ) ₃ . Further suitable mixed compounds are worth considering LnO (OH), LnOF, LnOCl, LnOBr, LnSF, LnSCl, LnSBr and Ln ₂ O ₂ S.

Preferably, in the process according to the invention, as component i) one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid chalcogenides, lanthanoid halides and mixed compounds of said lanthanoid compounds, in particular Preferably, one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid oxides, lanthanoid chlorides, lanthanoid bromides and mixed compounds of the above lanthanoid compounds are used. Particularly preferred lanthanoid compounds are in particular Ln (OH) ₃ , Ln ₂ O ₃ , LnCl ₃ , LnBr ₃ , LnO (OH), LnOCl and LnOBr which are already mentioned compounds of trivalent lanthanoids.

Very particular preference is given to using one or more lanthanum compounds as component i) in the process according to the invention, in which case the above preferences also apply for lanthanum compounds. Particularly suitable lanthanum compounds are La (OH) ₃ , La ₂ O ₃ , LaCl ₃ , LaBr ₃ , LaO (OH), LaOCl and LaOBr.

As component ii) of the process according to the invention, one or more compounds selected from the group consisting of crystalline boron, amorphous boron, boron carbides, borohydrides and boron halides are worth considering. Among the boron carbides, especially B ₄ C, among the borohydrides, especially B ₂ H ₆ , and among the boron halides, especially boron trifluoride, boron trichloride and boron tribromide. Can be mentioned.

  Preferably, in the process according to the invention and preferred embodiments thereof, as component ii) one or more compounds selected from the group consisting of crystalline boron, amorphous boron and boron halides, particularly preferably crystals One or more compounds selected from the group consisting of porous boron, amorphous boron, boron trichloride and boron tribromide are used.

  As component iii) of the process according to the invention, one or more reducing agents are optionally considered when selected from the group consisting of hydrogen, carbon, organic compounds, alkaline earth metals and alkaline earth metal hydrides.

  The organic compound as the reducing agent is, for example, a gaseous or liquid hydrocarbon. Here, aliphatic compounds having 1 to typically up to about 20 carbon atoms, such as alkanes such as methane, ethane, propane, butane, isobutane, octane and isooctane, alkenes and alkadienes such as ethylene, propylene , Butene, isobutene and butadiene, and alkynes such as acetylene and propyne, alicyclic compounds having 3 to typically 20 carbon atoms, such as cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane , Cycloheptane and cyclooctane, cycloalkene and cycloalkadiene such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene and cyclooctadiene and from 6 to Has up to 20 carbon atoms in, the aromatic, optionally more Kochijimi engaged hydrocarbons, such as benzene, naphthalene and anthracene. The alicyclic compound as well as the aromatic hydrocarbon may be further substituted with one or more aliphatic groups or may be condensed with the alicyclic compound. For example, here, possible reducing agents include toluene, xylene, ethylbenzene, tetralin, decalin and dimethylnaphthalene. Furthermore, mixtures of the aforementioned aliphatic compounds, alicyclic compounds and aromatic compounds are also considered as possible reducing agents. For example, here, mention may be made of mineral oil products such as petroleum ether, light benzine, medium benzine, solvent naphtha, coconut oil, diesel oil and heating oil.

  As reducing agents, organic liquids such as alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, s-butanol, pentanol, isopentanol, neopentanol and hexanol, glycols such as 1,2-ethylene glycol 1,2- and 1,3-propylene glycol, 1,2-, 2,3- and 1,4-butylene glycol, diethylene glycol and triethylene glycol and dipropylene glycol and tripropylene glycol, ethers such as dimethyl ether, diethyl Ether and methyl-t-butyl ether, 1,2-ethylene glycol monomethyl ether and 1,2-ethylene glycol dimethyl ether, 1,2-ethylene glycol monoethyl ether Ter and 1,2-ethylene glycol diethyl ether, 3-methoxypropanol, 3-isopropoxypropanol, tetrahydrofuran and dioxane, ketones such as acetone, methyl ethyl ketone and diacetone alcohol, esters such as acetic acid methyl ester, acetic acid ethyl ester, propyl acetate Esters or butyl acetate esters and natural oils such as olive oil, soybean oil and sunflower oil can also be used.

  With respect to the dispersion of components i), ii) and optionally iii) in the inert carrier gas, their collective state is important.

  In the case of solid substances, the dispersion of components i), ii) and optionally iii) can be carried out using corresponding equipment known to the person skilled in the art, for example a brush feeder or screw conveyor and subsequently a Flugstromfoerderung. Can be implemented. The solid material then forms with the carrier gas preferably an aerosol whose solid material particle size may be in the same range as the particle size of the nanoparticulate lanthanoid / boron-compounds obtainable by the process according to the invention. . In this case, the average agglomerated diameter of the solid component is typically 0.1 to 500 μm, preferably 0.1 to 50 μm, particularly preferably 0.5 to 5 μm. In the case of larger average agglomerate diameters, there is a risk of incomplete conversion to the gas phase, so such larger particles are not obtained for the reaction or are only obtained incompletely. In some cases, on incompletely evaporated particles, surface reactions can lead to their passivation.

  In the case of liquid substances, the dispersion in the form of vapors or droplets can likewise be carried out using corresponding devices known to those skilled in the art. For example, this is an evaporator, for example a thin film evaporator or flash evaporator, a combination consisting of a spray and jet evaporator, evaporation in the presence of an exothermic reaction (cold flame) and the like. The incomplete reaction of the sprayed liquid starting material is typically not a concern as long as the droplets have a particle size of less than 50 μm typical for aerosols.

  The various components i), ii) and optionally iii) may already be mixed and present in the carrier gas, however they may be introduced each time into a separate carrier gas stream, In the latter case, the mixing is preferably carried out before introduction into the reaction zone.

  Furthermore, the solid components i), ii) and / or optionally iii) can already be converted into the gas phase before being introduced into the reaction zone in the presence of a carrier gas. This is carried out, for example, using the same method used for the heat treatment of the mixture of components i), ii) and optionally iii) in the reaction zone in step b) of the process according to the invention. Can. Thus, components i), ii) and optionally iii) are preferably vaporized individually and in particular using microwave plasma, arc plasma, convective heating / radiant heating or autothermal reaction conditions and introduced into the carrier gas Can be done.

  As inert carrier gas, a noble gas such as helium or argon is usually used, or a noble gas mixture consisting, for example, of helium and argon. In special cases, nitrogen can also be used as a carrier gas, optionally in a mixture with the above-mentioned noble gases, but here at higher temperatures and components i), ii) and / or Or, depending on the nature of iii), the formation of nitrides must be prepared.

  When solid components i), ii) and optionally iii) are used and each time separately transported into the reaction zone by a carrier gas, the carrier gas load is usually 0.01 to 5 each time. 0.0 g / l, preferably 0.05 to 1 g / l. If solid components i), ii) and optionally iii) are used and are already transported as a mixture into the reaction zone by means of a carrier gas, the total amount of solid components i), ii) and optionally iii) The carrier gas load is usually 0.01 to 2.0 g / l, preferably 0.05 to 0.5 g / l.

  In the case of liquid and gaseous components i), ii) and optionally iii), generally higher loads are possible than those mentioned above. The load suitable for each processing condition can usually be easily calculated by a corresponding preliminary test.

  The ratio of component i) to component ii) is essentially dependent on the desired lanthanoid / boron compound stoichiometry. Typically, the lanthanoid hexaboride should occur as a stable phase or be obtained as a reaction product, so that one or more lanthanoid compounds of component i) and one or more boron of component ii) The compound is used in a molar ratio of Ln: B of about 1: 6. In the reaction product, the presence of by-products consisting of one of the reactants (ie component i) or component ii)) or of one of the compounds resulting from the reactant should be reduced or prevented For example, it may be advantageous to use the corresponding reactant (ie component ii) or component i) in a corresponding excess.

  The components i), ii) and optionally iii) introduced into the reaction zone are then reacted with each other in step c) of the process according to the invention by heat treatment, i.e. heating to a high temperature, in which case In particular, microwave plasma, arc plasma, convective / radiant heating, autothermal reaction conditions or combinations of the above methods are worth considering.

  Corresponding procedures and processing conditions for generating the components in the reaction zone by microwave plasma, arc plasma, convection heating / radiant heating, autothermal reaction conditions or a combination of the above methods are sufficient for those skilled in the art. Known to.

  Nanoparticulate lanthanoid / boron-compounds that are essentially isometric, ie essentially uniform in terms of their size and morphology, or corresponding solids containing essentially isometric nanoparticulate lanthanoid / boron-compounds In order to obtain a mixture, it is advantageous to stabilize the conditions in the reaction zone spatially and temporally as is generally known to those skilled in the art. This ensures that components i), ii) and optionally iii) are exposed to nearly identical conditions during this reaction and thus react to uniform product particles.

  The residence time of the mixture consisting of components i), ii) and optionally iii) in the reaction zone is usually from 0.002 s to 2 s, typically from 0.005 s to 0.2 s.

  In the case of autothermal reaction conditions, a mixture of hydrogen gas and halogen gas, in particular chlorine gas, is used in order to generate a flame. Furthermore, the flame can also be generated using a mixture of methane, ethane, propane, butanes, ethylene or acetylene, or alternatively a mixture of said gas and on the other hand oxygen gas, the latter being Is preferably used in a deficient amount in order to obtain reducing conditions in the reaction zone of the autothermal flame.

  Within one preferred embodiment, the heat treatment is performed by microwave plasma.

  As the gas or gas mixture for generating the microwave plasma, a rare gas such as helium or argon or a rare gas mixture consisting of helium and argon is usually used.

  In addition, a protective gas is typically used that covers the gas layer between the walls of the reactor used to generate the microwave plasma and the reaction zone, with the latter reaction zone essentially being free of microwave plasma. Corresponds to the range present in the reactor.

  The power introduced into the microwave plasma is typically in the range of a few kW to a few hundred kW. Higher power microwave plasma sources can also be used in principle for this synthesis. Furthermore, procedures for the generation of steady state plasma flames are well known to those skilled in the art, particularly with regard to the microwave power introduced, gas pressure, plasma gas and protective gas volume.

  In the course of the reaction in step b), after nucleation has taken place, nanoparticle primary particles are first produced, which are typically subject to further particle growth by the condensation and fusion processes. . Particle formation and particle growth are typically performed in all reaction zones, and may proceed further to rapid cooling after leaving the reaction zone. During this reaction, in addition to the desired lanthanoid / boron-compound, if further solid products are produced, the different primary particles formed can also agglomerate with each other, in the form of nanoparticles. A solid mixture results. If the formation of different solids during the reaction takes place at different times, the first primary particles of one product are surrounded by one or more other product layers. Coated products that have been applied can also be produced. Control of these agglomeration processes can be achieved, for example, by the chemistry of components i), ii) and optionally iii) in the carrier gas, the degree of loading of the carrier gas with said component, The reaction formation carried out depending on the presence of more than one component i), ii) and optionally iii) and their mixing ratio in them, the conditions of the heat treatment in the reaction zone, but also in step c) It can also be controlled by the type and timing of the object cooling.

  The cooling in step c) can be performed by direct cooling (rapid cooling), indirect cooling, expansion cooling (adiabatic pressure relief) or a combination of these cooling methods. In the case of direct cooling, the coolant is contacted directly with the hot reaction product to cool the product. In the case of indirect cooling, thermal energy is deprived from the reaction product without direct contact with the coolant. Indirect cooling typically allows for effective utilization of the thermal energy transferred to the coolant. To that end, the reaction product can be brought into contact with the exchange surface of a suitable heat exchanger. The heated coolant can be used, for example, for heating / preheating or evaporation of the solid, liquid or gaseous components i), ii) and optionally iii).

  The cooling condition in step c) is that in this case the reaction product consists essentially of an isometric nanoparticulate lanthanoid / boron-compound or consists essentially of an isometric nanoparticulate lanthanoid / boron-compound. Selected to contain. In particular, the primary particles cannot be deposited on the hot surface of the reactor used, and in particular when exposed to thermal conditions that favor the further directional growth of the primary particles. Must be taken care of.

  Preferably, the process according to the invention is carried out in step c) such that the reaction product obtained is cooled to a temperature in the range from 1800 ° C. to 20 ° C.

  In order to separate the reaction product obtained in step c), it is subjected to at least one separation step and / or purification step in step d). In that case, the formed nanoparticulate lanthanoid / boron-compound is isolated from the other components of the reaction product. For this purpose, customary separation devices known to those skilled in the art can be used, for example filters, cyclones, dry electrostatic precipitators or wet electrostatic precipitators or venturi scrubbers. Optionally, the formed nanoparticulate compound can be fractionated during the separation, for example by fractional precipitation. In principle, efforts should be made to obtain lanthanoid / boron-compounds with no by-products or at least only a small proportion of by-products, depending on the corresponding processing conditions and by the selection of particularly suitable starting materials. .

  The particle size of the nanoparticulate lanthanoid / boron compounds produced by the process according to the invention is usually in the range from 1 to 500 nm, in particular in the range from 2 to 150 nm. The nanoparticulate lanthanoid / boron-compound produced by the method according to the invention has a particle size distribution with a standard deviation σ of less than 1.5. A bimodal distribution can occur when solid by-products are generated, where the standard deviation σ of the lanthanoid / boron-compound is also less than 1.5.

  The method according to the invention can be carried out at any pressure. Preferably, it is operated within the range of 10 hPa to 5000 hPa. In particular, it is possible to carry out the process according to the invention at atmospheric pressure.

  The process according to the invention is suitable for the continuous production of essentially isometric nanoparticulate lanthanoid / boron compounds under essentially steady state conditions. Characteristic of this method is the rapid energy supply at high temperature levels, in the reaction zone to avoid agglomeration and especially directional growth of the formed nanoparticulate primary particles. Usually a uniform residence time of the starting material or reaction product under conditions and rapid cooling of the reaction product ("Abschrecken").

Examples Example 1:
A highly dispersible mixture consisting of 40% by weight of amorphous boron and 60% by weight of La ₂ O ₃ (molar ratio La: B = 1: 10) at a metering rate of 20 g / h is flowed into an Ar carrier gas stream (180 l / h) Supply to microwave plasma in. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As the reaction product, a mixture having a bimodal particle size distribution is obtained, which mainly consists of B ₂ O _{3 with} an average particle size of about 30 nm and LaB _{6 with} an average particle size of about 100 nm.

Example 2:
A highly dispersible mixture consisting of 39% by weight of amorphous boron and 61% by weight of CeO _{2 is} fed to the microwave plasma in an Ar carrier gas stream (180 l / h) at a metering rate of 20 g / h. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. The reaction product is a mixture with a bimodal particle size distribution, which mainly consists of B ₂ O _{3 with} an average particle size of about 30 nm and CeB _{6 with} an average particle size of about 100 nm.

Example 3:
A highly dispersible mixture consisting of 36% by weight of amorphous boron and 64% by weight of CeF _{3 is} fed to the microwave plasma in an Ar carrier gas stream (180 l / h) at a metering rate of 20 g / h. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. The reaction product is CeB ₆ with an average particle size of about 100 nm.

Example 4:
A highly dispersible mixture consisting of 39% by weight of amorphous boron and 61% by weight of Nd ₂ O _{3 is} fed into the microwave plasma in an Ar carrier gas stream (180 l / h) at a metering rate of 20 g / h. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As the reaction product, a mixture having a bimodal particle size distribution is obtained, which mainly consists of B ₂ O _{3 with} an average particle size of about 30 nm and NdB _{6 with} an average particle size of about 100 nm.

Example 5:
A highly dispersible mixture consisting of 35% by weight of amorphous boron and 65% by weight of NdF _{3 is} fed into the microwave plasma in an Ar carrier gas stream (180 l / h) at a metering rate of 20 g / h. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As a reaction product, NdB ₆ with an average particle size of about 100 nm is obtained.

Example 6:
A highly dispersible mixture consisting of 49% by weight of amorphous boron and 51% by weight of Y ₂ O _{3 is} fed into a microwave plasma in an Ar carrier gas stream (180 l / h) at a metering rate of 20 g / h. In addition, a flow of a gas mixture of 3.6 m ³ _N / h consisting of 75 vol% Ar, 10 vol% hydrogen and 15 vol% He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As the reaction product, a mixture having a bimodal particle size distribution is obtained, which mainly consists of B ₂ O _{3 with} an average particle size of about 30 nm and YB _{6 with} an average particle size of about 100 nm.

Example 7:
A highly dispersible mixture consisting of 36% by weight of amorphous boron and 64% by weight of YCl _{3 is} fed into the microwave plasma in a stream of Ar carrier gas (180 l / h) at a metering rate of 20 g / h. In addition, a flow of 3.6 m ³ _N / h of a gas mixture consisting of 75% by volume Ar, 10% by volume hydrogen and 15% by volume He is added to the plasma. This plasma is applied at an output of 30 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As a reaction product, YB ₆ having an average particle size of about 100 nm is obtained.

Example 8:
At a metering rate of 80 g / h, highly dispersible LaCl ₃ is mixed with a B ₂ H ₆ stream of 45 g / h (molar ratio La: B = 1: 10) with an Ar / H ₂ -carrier gas stream (640 l / h, It is supplied to the arc plasma in a molar ratio Ar: H ₂ = 10: 1. In addition, a 12 m ³ _N / h Ar flow is added to the plasma. This plasma is applied at an output of 70 kW. After the reaction, the reaction gas is quenched very quickly and the resulting particles are separated. As the reaction product, a mixture with a bimodal particle size distribution is obtained, which mainly consists of B ₂ O _{3 with} an average particle size of about 20 nm and LaB _{6 with} an average particle size of about 70 nm.

Claims (10)

In a process for producing an essentially isometric nanoparticulate lanthanoid / boron-compound or a solid mixture containing essentially isometric nanoparticulate lanthanoid / boron-compound,
a) i) one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid hydrides, lanthanoid chalcogenides, lanthanoid halides, lanthanoid borates and mixtures of the above lanthanoid compounds,
ii) one or more compounds selected from the group consisting of crystalline boron, amorphous boron, boron carbides, borohydrides and boron halides and iii) hydrogen, carbon, organic compounds, alkaline earths Optionally, one or more reducing agents selected from the group consisting of metals and alkaline earth metal hydrides are dispersed in an inert carrier gas and mixed together;
b) reacting a mixture of components i), ii) and optionally iii) in an inert carrier gas with each other by heat treatment in the reaction zone;
c) subjecting the reaction product obtained by heat treatment in step b) to rapid cooling, and d) subsequently causing separation of the cooled reaction product in step c),
In so doing, the cooling conditions in step c) are such that the reaction product consists essentially of isometric nanoparticulate lanthanoid / boron-compound or contains essentially isometric nanoparticulate lanthanoid / boron-compound. Characterized to choose to,
Process for the production of a solid mixture containing essentially isometric nanoparticulate lanthanoid / boron-compound or essentially isometric nanoparticulate lanthanoid / boron-compound.   In step b), the heat treatment of the mixture of components i), ii) and optionally iii) in an inert carrier gas can be carried out by microwave plasma, arc plasma, convection heating / radiant heating, autothermal reaction conditions or the above process. The method of claim 1, wherein the methods are produced by a combination.   The process according to claim 1, wherein in step b) the heat treatment of the mixture of components i), ii) and optionally iii) in the inert carrier gas is effected by microwave plasma.   The process according to any one of claims 1 to 3, wherein in step c), the reaction product obtained is cooled to a temperature in the range from 1800 ° C to 20 ° C.   The component i) uses one or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid chalcogenides, lanthanoid halides and mixed compounds of said lanthanoid compounds. The method of any one of Claims.   2. One or more lanthanoid compounds selected from the group consisting of lanthanoid hydroxides, lanthanoid oxides, lanthanoid chlorides, lanthanoid bromides and mixed compounds of said lanthanoid compounds are used as component i). 5. The method according to any one of items 4 to 4.   7. The process as claimed in claim 1, wherein one or more lanthanum compounds are used as component i).   8. A process according to any one of claims 1 to 7, wherein as component ii) one or more compounds selected from the group consisting of crystalline boron, amorphous boron and boron halides are used.   8. One or more compounds selected from the group consisting of crystalline boron, amorphous boron, boron trichloride and boron tribromide are used as component ii). The method described.   The process according to any one of claims 1 to 9, which is carried out within a pressure range of 500 hPa to 2000 hPa.